Resin materials, especially transparent resin materials represented by polycarbonate and the like have such characteristics as low specific gravity, low weight, easy processability, and better impact resistance compared with inorganic glass, and therefore are widely used in various applications. Recently, from the viewpoints of saving petroleum sources and reducing carbon dioxide discharge quantity, a tendency to attempt to lower the weight of vehicle window glasses, interior and exterior materials and the like by replacing with plastics and to improve fuel efficiency is increasing.
To the contrary, a resin material has disadvantages, such as, the surface thereof is easily damaged and the gloss or transparency is easily lost, it is easily invaded by organic solvents, and its weather resistance (for example, light stability with regard to rays such as ultraviolet rays) and heat resistance are poor, etc. Window glasses and the like for vehicle are often exposed to sunlight for a long period of time. Accordingly, in the case of using a resin material for a vehicle member, it is necessary to provide its surface with abrasion resistance and weather resistance by means of covering the surface with a protective film and so on.
As a protective film having excellent abrasion resistance and weather resistance, for example, a hard coating layer obtained by curing a light-curing coating agent composition may be exemplified.
As a light-curing coating agent composition having both abrasion resistance and weather resistance, a composition for forming an abrasion-resistant coating is known (patent document 1), which contains colloidal silica particles whose surfaces are modified with a silane compound having a methacryloyloxy group, an acryloyloxy group or a vinyl group in predetermined proportion by weight, a monomer mixture comprising a poly[(meth)acryloyloxyalkyl]isocyanurate and a urethane (poly)methacrylate having an alicyclic skeleton, and a photopolymerization initiator, in a specific proportion.
Furthermore, a coating agent composition is also known (patent document 2), which contains, in specific proportion, a poly(meth)acrylate of mono- or poly-pentaerythritol, a urethane poly(meth)acrylate having at least two radical polymerizable unsaturated double bonds, a poly[(meth)acryloyloxyacryl](iso)cyanurate, an ultraviolet absorber, a hindered amine based light stabilizer and a photopolymerization initiator.
There is also an example in which a thermocuring coating agent composition is used. In patent document 3, a plastic article is disclosed, wherein the plastic article comprises, on a surface thereof, a first layer formed by curing a thermocuring undercoating composition having an excellent weather resistance, and a second layer on the first layer formed by curing a thermocuring coating agent composition having an excellent abrasion resistance.